Iron-based amorphous alloy having low stress sensitivity, and preparation method therefor

ABSTRACT

An iron-based amorphous alloy. The iron-based amorphous alloy comprises components Fe a B b Si c , a, b and c respectively indicating atomic percentage contents, 79.5≤a≤82.5, 11.0≤b≤13.5, 6.5≤c≤8.5, and a+b+c=100. An iron-based amorphous alloy strip is obtained by means of a rapid quenching method in which a single roller is used. Because the iron-based amorphous alloy has higher saturated magnetic induction density, a higher amorphous formation capability and lower stress-resistance sensitivity, the iron-based amorphous alloy can be used as an iron core material for preparing a power transformer, a power generator and an engine; in addition, due to the low stress sensitivity of the iron-based amorphous alloy, the sudden short-circuit resistance capability of an amorphous transformer can be improved when the power transformer is prepared.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Chinese Patent Application No.201710447487.1, filed on Jun. 14, 2017, and titled with “IRON-BASEDAMORPHOUS ALLOY HAVING LOW STRESS SENSITIVITY, AND PREPARATION METHODTHEREFOR”, and the disclosures of which are hereby incorporated byreference.

FIELD

The present disclosure relates to the field of iron-based amorphousalloy technology, especially to an iron-based amorphous alloy having lowstress sensibility, and a method for preparing the same.

BACKGROUND

Due to its low iron loss, high saturation magnetic flux density, highpermeability, and other advantages, Fe-based amorphous alloy strips suchas Fe-Si-B amorphous alloys are widely used as iron cores for powertransformers and high-frequency transformers. Based on the abovecharacteristics, iron-based amorphous materials have taken the lead inthe transformer field for a long period of time ever since they wereinvented.

With the continuous renewal of silicon steel materials, the advantagesof amorphous materials are relatively weakened. For example, amorphousmaterials have significantly low saturated magnetic density, lowmagnetic induction, poor anti-stress sensibility and so on. In recentyears, a lot of works have been done to improve the saturation magneticinduction and reduce the loss of amorphous materials, but there is nonoticeable result for the study of the anti-stress sensibility ofamorphous materials. The stress removal is the fundamental guarantee ofthe low loss characteristics of amorphous materials. In addition, as amain material of the transformer magnetic circuit, the thickness of theamorphous alloy strip is 20-30 μm. Because it is hard and brittle anddifficult to be cut, the cross section of iron core of amorphous alloytransformer is rectangular, so that the corresponding high and lowvoltage windings are rectangular. Rectangular windings have relativelypoor ability to withstand short circuits with respect to the circularwindings, so it is necessary to improve the ability of the amorphousalloy transformers to withstand short-circuits.

The stress of the amorphous transformer core is mainly composed of twoparts of stress, one is the internal stress generated during thepreparation process of amorphous material, i.e., the internal stressgenerated during quenching of the amorphous material, the other is anunavoidable assembly external stress due to the characteristics of theiron core during the manufacturing process of the iron core. A largenumber of researches for reduce the stress mainly focus on the annealingprocess and optimizing the transformer core structure.

The internal stress generated during quenching of amorphous materials ismainly related to the formation of amorphous materials. Rapid cooling isa necessary condition for the formation of amorphous materials. When ahigh-temperature molten material is poured onto a cooling substrate andcooled at a speed of 10⁶° C./s, an amorphous strip with a short-rangeorder and long-range disorder structure is formed. This short-rangedisorder liquid is “frozen,” and internal stresses are generated inthese “frozen” structures. The internal stress of the amorphous materialcan be effectively removed through the annealing process, and theamorphous industry has done a lot of works to remove the internal stressthrough the annealing process. When the internal stress generated duringquenching is removed by annealing, thermal stress is induced by thelarge difference of the temperature in core at the same time, i.e., theinternal stress cannot be completely removed.

The assembly external stress is mainly caused by the process ofproducing the iron core from the amorphous strip during core assemblyand the external stress caused by the structural characteristics of thecore itself. This kind of stress is unavoidable and there is littlestudy on the removal of it, which is mainly through the optimization ofthe iron core structure of the transformer and the specification of theoperation. Amorphous alloy transformer windings have a rectangularstructure, and the electric power received by them is far less uniformthan that of a circular winding of ordinary transformers. It is easierto be deformed when subjected to sudden short circuit electric power.Since the iron core material of amorphous alloy transformer is verysensitive to mechanical stress, both tensile and bending stress willaffect its performance, which should be fully considered in thestructure design to reduce the force on the iron core. Generally,special fastening designs are used, and the amorphous alloy transformerbody is an axial bearing structure. The stresses on the amorphous alloycore and the rectangular windings do not interfere with each other. Therectangular windings are pressed by the upper and lower clamps and thepressure plate to form a compression structure by itself. Therefore, itsuffers more from the short-circuit electric power in the axial andradial directions of the rectangular winding than the circular winding.In order to reduce the difficulty in the assembly and design of thetransformer, it is important to reduce the stress sensibility of theamorphous alloy.

For example, Japanese Patent No. JPS63-45318 discloses a method forimproving the annealing process, mainly by reducing the temperaturedifference in the iron core. In this method, a heat insulating materialis installed on the inner and outer circumferential surfaces of the ironcore to minimize the temperature difference in the iron core duringcooling, so as to improve the properties of thin strip itself andimprove the weight and bulk of the iron core. Iron core is put into aheat treatment furnace and heated, and temperature variation occurs invarious parts of the iron core. Annealing and removing stress in thismethod does not cause crystallization due to excessive core temperaturein the furnace or does not cause the phenomenon of incomplete stressremoval due to low temperature. However, the specific procedures of thismethod are not described in the disclosure, and the process of annealingthe iron core and the annealing cost are increased, so that it is notpractical in actual annealing process.

The Chinese Patent No. CN1281777 C discloses that by adding a specificrange of P in the restricted ranges of Fe, Si, B, and C, it is foundthat under the situation of uneven temperature in various parts of theiron core during annealing, iron core annealing at lower temperaturescan also exhibit excellent soft magnetic properties. The inventors onlyconsidered the effect of P on reducing the temperature unevenness of theamorphous iron core, and not the problems of oxidation and surfacecrystallization of the phosphorus-containing amorphous strip. Theelement P has extremely poor oxidation resistance. When annealing in anaerobic environment, the performance and the apparent quality of ironcore will easily become worse due to oxidation. For example, whenphosphorus-containing amorphous materials are annealed under theconditions for Fe, Si, B, and C annealing, the surfaces of the stripbecome blue due to oxidation, and the performance deteriorates. This hasvery strict requirements for the oxygen content of the annealingatmosphere. At present, there is no preparation of ferrophosphorus ofthe amorphous strip, and the introduction of phosphorus and iron willgenerate unavoidable impurities, and the crystallization on the stripsurface will easily occur. In summary, the above method avoids thedefects of large temperature difference inside the iron core, butintroduces problems such as oxidation during annealing and of theamorphous strip and crystallization on the strip surface.

The U.S. Patent Publication No. US20160172087 discloses the study of thestress release based on different components, pointing out the effect ofB and C on the stress release, and illustrating the amount of stressreleased after the strip annealing through an experimental model.However, the inventor only explained the degree of stress release fromthe point of internal stress removing and stress release after annealingfrom a single strip, without considering the final soft magneticproperties of the material and the performance deterioration of thetransformer core due to the assembly stress.

In view of the above, although the embodiments of the above disclosureshave optimized the annealing process or the assembly process of theamorphous transformer iron core and the stress of the amorphous stripcan be removed to a great extent. However, the feasibility of strippreparation and implementation of these optimizations are notspecifically considered, and a more comprehensive understanding of thestress relieving (stress avoidance) of amorphous strips is missing. Theresults are relatively one-sided.

SUMMARY

The technical problem solved by the present disclosure is to provide aniron-based amorphous alloy strip, and the iron-based amorphous alloystrip of the present disclosure has relatively low stress sensibility.

In view of this, the present disclosure provides an iron-based amorphousalloy represented by formula (I):

Fe_(a)B_(b)Si_(c)   (I);

wherein a, b and c are each independently atomic percentages ofcorresponding components; 79.5≤a≤82.5, 11.0≤b≤13.5, 6.5≤c≤8.5, anda+b+c=100.

Preferably, the saturation magnetic induction of the iron-basedamorphous alloy is ≥1.60 T.

Preferably, the atomic percentage of Fe is 80.0≤a≤81.5.

Preferably, the atomic percentage of B is 11.0≤b≤12.5.

Preferably, the atomic percentage of Si is 7.0≤c≤8.0.

Preferably, in the iron-based amorphous alloy, a=80.0, 12.0≤b≤13.0,7.0≤c≤8.0.

Preferably, in the iron-based amorphous alloy, a=80.5, 11.5≤b≤12.5,7.0≤c≤8.0.

Preferably, in the iron-based amorphous alloy, 81.0≤a≤81.5, 11.0≤b≤13.0,7.0≤c≤8.0.

The present disclosure further provides a method for preparing theiron-based amorphous alloy strip represented by formula (I), comprising:

preparing raw materials according to the atomic percentages indicated informula (I); smelting the raw materials; heating and insulating themolten liquid after smelting; performing single roller rapid quenchingto obtain an iron-based amorphous alloy strip;

Fe_(a)B_(b)Si_(c)   (I);

wherein a, b and c are each independently atomic percentages ofcorresponding components; 79.5≤a≤82.5, 11.0≤b≤13.5, 6.5≤c≤8.5, anda+b+c=100.

Preferably, after the single roller rapid quenching, the iron-basedamorphous alloy is subjected to heat treatment.

Preferably, prior to the heat treatment, the iron-based amorphous alloyis winded into a sample ring with an inside diameter of 50.5 mm and anoutside diameter from 53.5 to 54 mm.

After heat treatment, the allowable gauge factor of the sample ring lossis 10.0%, and allowable gauge factor of the excitation power is 6%.

Preferably, coercive force of the heat treated iron-based amorphousalloy strip is ≤3.5 A/m; under a condition of 50 Hz and 1.35 T,excitation power of the heat treated iron-based amorphous alloy strip is≤0.1450 VA/kg, and core loss is ≤0.1100 W/kg; and under a condition of50 Hz and 1.40 T, excitation power of the heat treated iron-basedamorphous alloy strip is ≤0.1700 VA/kg, and core loss is ≤0.1500 W/kg.

Preferably, the iron-based amorphous alloy strip is in completelyamorphous phase with a limit thickness of at least 75 nm and a shearinglimit strip thickness of at least 29 nm.

The present disclosure provides an iron-based amorphous alloy strip,which has an atomic composition represented by formulaFe_(a)B_(b)Si_(c), wherein a, b and c are each independently atomicpercentages of corresponding components; 79.5≤a≤82.5, 11.0≤b≤13.5,6.5≤c≤8.5, and a+b+c=100; Fe in the iron-based amorphous alloy providedby the present disclosure ensures obtaining stable amorphous iron-basedalloys having lower preparation requirements and higher yield; Sielement is conducive to the stable formation of amorphous materials; andB is the element that contributes most to the amorphousness of thealloy. Thus, by adjusting the contents of Fe, Si, and B, the presentdisclosure prepares an iron-based amorphous alloy having high saturationmagnetic induction strength, high ductility and low stress sensibility,which makes the transformer assembled by the iron core made from thealloy having strong sudden short circuit resistance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of the simulation experiment equipment forthe iron-based amorphous alloy sample ring prepared in the presentdisclosure under condition of no stress.

FIG. 2 is a schematic diagram of the simulation experiment equipment forthe iron-based amorphous alloy sample ring prepared in the presentdisclosure under condition of stress.

DETAILED DESCRIPTION

In order to further understand the present disclosure, the preferredembodiment of the present disclosure is described hereinafter inconjunction with the examples of the present disclosure. It is to beunderstood that the description is merely illustrating the charactersand advantages of the present disclosure, and is not intended to limitthe claims of the present disclosure.

Either internal stress or external stress is inevitable. Stress stillexists after optimizing the annealing process, optimizing the iron-corestructure of transformer and standardizing the operation. A main objectof the present disclosure is to establish a range of amorphouscomposition having low stress sensibility through adjusting componentsand evaluating the stress (internal stress and external stress) of stripwith different components, so as to effectively show excellent softmagnetic properties of amorphous products, and produce an amorphoustransformer that has a relatively good ability of withstanding suddenshort-circuit. Thus, the present disclosure discloses an iron-basedamorphous alloy represented by formula (I):

Fe_(a)B_(b)Si_(c)   (I);

wherein a, b and c are each independently atomic percentages ofcorresponding components; 79.5≤a≤82.5, 11.0≤b≤13.5, 6.5≤c≤8.5, anda+b+c=100.

The iron-based amorphous alloy provided by the present disclosurecomprises Fe, Si and B, and through adjusting the content of the aboveelements to give alloy a relatively good glass forming ability,saturation magnetic induction and soft magnetic property. Furthermore,after heat treatment, the strip made of the iron-based amorphous alloyprovided by the present disclosure has relatively low anti-stresssensibility.

In the iron-based amorphous alloy, Fe is the base element, and thecontent of it is 79.5≤a≤82.5 by atomic percentage. If the atomicpercentage of Fe is unduly low, the saturation magnetic induction of theiron-based amorphous alloy will be unduly low, so that it cannot improvethe defect of low magnetic flux density of the amorphous and cannotobtain enough magnetic flux density and an iron core with compactstructure. When the content is unduly high, the thermal stability ofiron-based amorphous alloy and the formability of strip are decreased,making it hard to smooth operation of the strip and obtain a goodmagnetic product. In the embodiments, the atomic percentage of Fe is79.5≤a≤81.5, more specifically, the atomic percentage of Fe is80.0≤a≤81.5.

The atomic percentage of Si is 6.5≤c≤8.5. When the content is undulylow, the formability of iron-based amorphous alloy strip and the thermalstability of amorphous alloy strip are decreased, making it hard to forma stable amorphous material. When the content is unduly high, thebrittleness of the iron-based amorphous alloy becomes high, and theductility of the annealed strip becomes worse. In the embodiments, thecontent of Si is 7.0≤c≤8.0.

The atomic percentage of B is 11.0≤b≤13.5. When the content of B isunduly low, it is hard to form a stable amorphous material. When thecontent is unduly high, the ability of forming amorphous state does notfurther improve, i.e., the content of B in the above range gives theiron.-based amorphous alloy of the present disclosure excellent softmagnetic property. In embodiments, the content of B is 11.0≤b≤13.0, morespecifically, the content of B is 11.0≤b≤12.5.

In the present disclosure, a preferably composition of the iron-basedamorphous alloy is: a=80.0, 12.0≤b≤13.0, and 7.0≤c≤8.0; or a=80.5,11.5≤b≤12.5, and 7.0≤c≤8.0; or 81.0≤a≤81.5, 11.0≤b≤13.0, and 7.0≤c≤8.0.

The iron-based amorphous alloy composition and contents provided by thepresent disclosure is a reasonable combination of improving magneticinduction and improving glass forming ability, forming an iron-basedamorphous alloy with high saturation magnetic induction. Further, on thebase of high saturation magnetic induction, the iron-based amorphousalloy of the present disclosure also has low stress sensibility. Thereason why the iron-based amorphous alloy provided by the presentdisclosure has high saturation magnetic induction and low stresssensibility is due to the adjustment of the composition and content ofthe iron-based amorphous alloy.

The present disclosure further provides a method for preparing theiron-based amorphous alloy strip represented by formula (I), comprising:

preparing raw materials according to the atomic percentage of formula(I); smelting the raw materials; heating and insulating the moltenliquid after smelting; performing single roller rapid quenching toobtain an iron-based amorphous alloy strip;

Fe_(a)B_(b)Si_(c)   (I);

wherein a, b and c are each independently atomic percentages ofcorresponding components; 79.5≤a≤82.5, 11.0≤b≤13.5, 6.5≤c≤8.5, anda+b+c=100.

In the process of preparing the iron-based amorphous alloy strip,conventional methods in the art are used to prepare the iron-basedamorphous alloy strip with the specific composition of the presentdisclosure. The preparing and smelting processes above are well known toone of ordinary skill in the art, which would not be descripted indetails in the present disclosure. In the smelting process, the metalraw materials are smelted in a medium frequency furnace, and thesmelting temperature is from 1300 to 1500° C., and the duration is from80 to 120 minutes. After smelting, in the present disclosure, the moltenmaterial is heated and insulated, and subjected to single roller rapidquenching, so as to obtain the iron-based amorphous alloy strip. Theheating temperature is preferably from 1350 to 1470° C., and theinsulating duration is preferably from 20 to 50 minutes. After singleroller rapid quenching, an iron-based amorphous alloy strip is obtainedin completely amorphous state, and limit thickness of the formedamorphous is at least 75 μm, and toughness of the strip is relativelygood, which will not crack after 180 degree folding.

For the present disclosure, the shearable limit thickness of the stripis at least 29 μm, so that the present product has pretty largeproduction margin in industrial production and requirement of thecooling equipment in the industrial process is decreased.

In the present disclosure, after the raw iron-based amorphous alloystrip is prepared, it is subjected to heat treatment for ease ofapplication. The iron-based amorphous alloy provided by the presentdisclosure is capable to be treated in a relatively wide annealingrange, and the iron-based amorphous alloy strip obtained has relativelylow excitation power and loss. In the present disclosure, the heattreatment temperature is from 325 to 395° C.; and in embodiments, theheat treatment temperature is from 335 to 385° C.

According to the present disclosure, prior to the heat treatment, theobtained iron-based amorphous alloy is preferably winded into a samplering with an inside diameter of 50.5 mm and an outside diameter of from53.5 to 54 mm, and then the above sample ring is subjected to heattreatment.

Loss and deterioration of excitation power of the heat treated samplering under conditions of stress are detected through simulationexperiments, so as to illustrate transition of the properties ofiron-based amorphous alloy strip under condition of stress. If the lossand the deterioration coefficient of excitation power of the iron-basedamorphous alloy strip still lay in an acceptable range under conditionswith a relatively large gauge factor, the iron-based amorphous alloystrip has relatively low stress sensibility. If the loss and thedeterioration coefficient of excitation power of the iron-basedamorphous alloy strip are unacceptable when the gauge factor isrelatively small, the stress sensibility of the iron-based amorphousalloy strip is relatively bad. Through the simulation experiment of thepresent disclosure, the experiment results show that the iron-basedamorphous alloy strip has relatively low stress sensibility.

In the present disclosure, by adjusting the components and content ofthe components, i.e., components and content of the components cooperatewith each other, the magnetic property of the iron-based amorphous alloyis improved and the stress sensibility of the iron-based amorphous alloystrip is decreased at the same time.

In order to understand the present disclosure better, the iron-basedamorphous alloy will be illustrated in details in conjunction withembodiments hereinafter, and the protection scope of the presentdisclosure is not limited by the following embodiments.

EXAMPLE 1) Preparation of the Iron-Based Amorphous Alloy Strip

According to the alloy components represented by formulaFe_(a)B_(b)Si_(c), industrial pure iron, silicon and boron were used toprepare the alloys shown in Table 1. Except for the main elements, thereare unavoidable impurity elements in the alloys, such as C, Mn, S, andso on. The materials with different components were successively addedto a medium frequency furnace of a furnace volume of 100 kg in the orderof boron iron, silicon and pure iron for remelting (the smeltingtemperature was from 1300 to 1500° C., and the duration was from 80 to120 minutes). After holding, the molten steel was casted to the sprayingladle for producing an amorphous strip with a width of 20 mm by singleroller planar flow casting. In the strip producing process, alloy stripswith different thicknesses were produced by adjusting parameters such asroller speed, liquid level and so on (in the strip producing process,the roller speed was from 1000 to 1400 r/min, and the linear speed ofthe strip producing is from 20 to 30 m/s, and the liquid level was from200 mm to 300 mm).

2) Test of Glass Forming Ability and Saturation Magnetic Induction ofIron-Based Amorphous Alloy Strip

XRD was used to test the free face of strips with different componentsuntil the strip thickness was in the amorphous state. Table 1 showed thelimit thicknesses of each strip with different amorphous alloycompositions. The saturation magnetization induction of the amorphousalloy strips were measured with VSM. The alloy compositions werecomprehensively evaluated by the glass forming ability and saturationmagnetic induction of the strips. According to the number of brittlepoints, maximum shearing thickness of the strip was evaluated. Themethod for evaluating brittle point is: taking the strip which has alength equal to the perimeter of the crystallizer and shearing the stripalong the longitudinal direction. When the number of the brittle pointwas not more than 2, the strip was considered to be shearable, and whenthe number of the brittle point was 2, the length was regarded as theshearable limit thickness of the alloy strip.

TABLE 1 iron-based amorphous alloy with different compositions and theirproperties Limit Thickness Shearable of the Obtained limit CompositionAmorphous Strip thickness Bs Group Fe Si B (μm) (μm) (T) Example 1 80.08.0 12.0 80 30 1.60 Example 2 80.0 7.5 12.5 82 29 1.60 Example 3 80.07.0 13.0 80 30 1.61 Example 4 80.5 8.0 11.5 80 30 1.61 Example 5 80.57.5 12.0 80 33 1.62 Example 6 80.5 7.0 12.5 80 33 1.62 Example 7 81.08.0 11.0 75 32 1.62 Example 8 81.0 7.5 11.5 75 32 1.62 Example 9 81.07.0 12.0 75 33 1.62 Example 10 81 6.5 12.5 75 33 1.63 Example 11 81.57.0 11.5 65 38 1.62 Comparative 78.0 9.0 13.0 85 26 1.55 Example 1Comparative 79.5 9.5 11.0 80 27 1.56 Example 2 Comparative 79.0 9.0 12.080 27 1.56 Example 3 Comparative 80.0 9.0 11.0 75 26 1.57 Example 4Comparative 80.0 6.0 14.0 78 30 1.61 Example 5 Comparative 80.5 9.0 10.575 25 1.58 Example 6 Comparative 80.5 6.0 13.5 80 32 1.63 Example 7Comparative 82.0 6.0 12.0 50 36 1.63 Example 8 Comparative 83.0 6.5 10.545 37 1.64 Example 9

Table 1 showed the limit thickness of the amorphous strips, toughnesslimit thickness of strip producing and saturation magnetic induction ofalloys with different compositions. The amorphous strip limit thicknessand the toughness limit thickness of strip producing are the tests forstrip producing technology. The thicker the strip thickness was, themore relax the requirement for the strip producing equipment was.

Under the same strip producing condition, the thicker the amorphousstrip limit thickness of the alloy, the higher the degree ofnon-crystallinity of strip was. Although comparative examples 1 to 4have a relatively high amorphous strip limit thickness, the maximumshearing thickness was below 27 μm. This not only puts more stringentrequirements on the cooling intention of the strip producing equipment,but also influences the assembly efficiency of iron core. At the sametime, it also carried foreshadows of breaking in assembly and operationprocess of transformer, leading to an increasing of potential safetyhazard in operation of transformer. In addition, the saturation magneticinduction was less than 1.57 T, giving less flexibility to the design ofamorphous transformers, and could not meet the design trend of high fluxdensity of transformers. Comparing the comparative example 6 with theexamples 4 to 6, it could be concluded that when the content of Fe wasthe same, the higher the content of Si was, the thinner the shearingthickness was.

In the comparative examples 8 to 9, the relatively high saturationmagnetic induction of the amorphous alloy was expected for the design oftransformer. The maximum shearing thickness was between 36 and 38 μm,which was absolutely superior in terms of efficiency in core molding.However, its amorphous forming ability was obviously insufficient basedon the limit thickness of the amorphous strip, so it did not meet therequirements for smooth operation of producing strip and it alsoaffected its excitation power and loss.

It could be concluded from Table 1 that from the comprehensiveconsideration of smooth operation of strip producing and transformerdesign, the alloy compositions of examples 1 to 11 have a smoothoperation performance and a wide range of transformer design.

Strips with a thickness of 26 to 28 μm and a width of 30 mm in Table 1were wound into sample rings with an inner diameter of 50.5 mm and anouter diameter of 53.5 to 54 mm. The sample rings were subjected tostress relief annealing using a box type annealing furnace.

Annealing was carried out under the protection of argon-with atemperature from 325 to 395° C. at an interval of 10° C. and 1 hourinsulation. A magnetic field along the direction of strip preparing wasadded during the heat treatment process with a magnetic field strengthof 1200 A/m. The silicon steel tester was used to test the excitationmagnetic and loss of the strip after heat treatment. The test conditionswere 1.35 T/50 Hz and 1.40 T/50 Hz respectively. The test results of thecharacteristic tests were shown in Table 2.

TABLE 2 Property data of the samples and the comparative samples afterthe heat treatment 1.35 T/50 Hz 1.4 T/50 Hz Composition Pe P Pe P GroupFe Si B (VA/kg) (W/kg) (VA/kg) (W/kg) Example 1 80.0 8.0 12.0 0.1300.099 0.170 0.130 Example 2 80.0 7.5 12.5 0.135 0.098 0.165 0.133Example 3 80.0 7.0 13.0 0.128 0.103 0.168 0.140 Example 4 80.5 8.0 11.50.132 0.102 0.165 0.138 Example 5 80.5 7.5 12.0 0.125 0.085 0.145 0.115Example 6 80.5 7.0 12.5 0.120 0.090 0.150 0.118 Example 7 81.0 8.0 11.00.140 0.108 0.158 0.135 Example 8 81.0 7.5 11.5 0.138 0.100 0.162 0.130Example 9 81.0 7.0 12.0 0.133 0.105 0.165 0.139 Example 10 81 6.5 12.50.135 0.102 0.160 0.138 Example 11 81.5 7.0 11.5 0.140 0.106 0.165 0.145Comparative 78.0 9.0 13.0 0.156 0.138 0.230 0.165 Example 1 Comparative79.5 9.5 11.0 0.141 0.123 0.223 0.167 Example 2 Comparative 79.0 9.012.0 0.145 0.121 0.215 0.154 Example 3 Comparative 80.0 9.0 11.0 0.1360.104 0.187 0.150 Example 4 Comparative 80.0 6.0 14.0 0.146 0.110 0.1700.150 Example 5 Comparative 80.5 9.0 10.5 0.142 0.125 0.225 0.155Example 6 Comparative 80.5 6.0 13.5 0.130 0.093 0.154 0.120 Example 7Comparative 82.0 6.0 12.0 0.169 0.148 0.189 0.165 Example 8 Comparative83.0 6.5 10.5 0.167 0.145 0.187 0.170 Example 9

It could be concluded form the Table 2 that under the condition of 1.35T/50 Hz, the loss values of comparative examples 1 to 3 and comparativeexamples 8 to 9 were relatively high, and the performance was above 0.12W/kg; and under the condition of 1.4 T/50 Hz, the excitation and loss ofcomparative examples 1 to 4 and 6 were significantly higher than that of1.35 T/50 Hz, and were significantly higher than other samples at 1.4T/50 Hz, and this was mainly related to the low saturated magnetic fluxdensity of the above samples. The excitation magnetic and loss of theamorphous material increase with the increase of the magnetic density.Especially, the performance of excitation power was particularlyprominent. Comparing with materials with low saturation magneticinduction, amorphous materials with high saturation magnetic inductionallow a greater working magnetic density, i.e., showing relatively lowexcitation power and losses at magnetic density of 1.4 T. Normallyspeaking, the comparative examples 8 to 9 show a better performance at1.4 T test. However, due to the relative large values of them at 1.35 T,the loss and excitation magnetic at 1.4 T increased, resulting in arelatively large value at 1.4 T.

Examples 1 to 11 exhibited excellent soft magnetic properties at 1.35T/50 Hz and 1.40 T/50 Hz; loss at 1.35 T/50 Hz was below 0.11 W/kg, andloss at 1.40 T/50 Hz was below 0.15 W/kg.

3) Test of Stress Sensibility

The study above mentioned that amorphous materials have relatively lowunavoidable loss values, and the performances of amorphous materialswere deteriorated by external stress after they were assembled into aniron core. In the present study, a stress model of amorphous sample ringwas established to characterize the performance deterioration ofamorphous alloys with different compositions after stress deformation,and simulated the performance changes caused by stress when amorphousstrip assembled into transformer cores.

Sample processing: the amorphous strips listed in Table 3 were selected,wound into a sample ring with an inner diameter of 50.5 mm and an outerdiameter of 53.5 to 54 mm, and subjected to stress removing andannealing with a box annealing furnace under the protection of argon.Sample rings prepared with different compositions were chosen, andsubjected to heat treatment according to the above requirements. Thethermal insulation temperature of the heat treatment was from 325 to395° C. with 5° C. as a gradient for the heat treatment, the insulationduration was from 60 to 120 min, and the magnetic field strength wasfrom 800 to 1400 A/m. The optimal heat treatment performances of eachcomponent in the above heat treatment process were chosen to test theperformance deterioration of the strip after stress.

The application of stress was considered by calculating the retractiondistance of the circular strip. The feed amount of the sample ring wascalculated according to the deformation coefficient formula. As shown inFIG. 1, FIG. 1 was a schematic diagram of the simulation experimentequipment of the sample ring under condition of no stress, and FIG. 2was a schematic diagram of the simulation experiment equipment of thesample ring under condition of stress. When the sample ring was understress, the A plate was fixed, and the feeding amount of the sample ringwas given with the action of pushing plate B. The sample ring wasdeformed by the stress, and the pushing plate B was fixed. The loss P₁and excitation power Pe₁ of the material under deformation conditionswere measured, and the performance of the sample at 1.35 T/50 Hz wastested with a silicon steel tester.

The initial sample ring (without deformation) has an inner diameter ofD₀ and performance values of P₀ and Pe₀ respectively. After deformation,the inner diameter was D₁, and the performance values were P₁ and Pe₁respectively. The gauge factor=(D₁−D₀)*100%/D₀. The loss deteriorationcoefficient=(P₁−P₀)*100%/P₀. The excitation power deteriorationcoefficient=(Pe₁−Pe₀)/Pe₀.

Comprehensively considering the difference of the selected performancesand the permissible degree of deterioration of the performance afterdeformation, this experiment stipulated that the performancedeterioration within 50% was an acceptable range, and the sample ringdeformation corresponding to the performance value was the maximumallowable deformation coefficient value of the corresponding componentmaterial.

It could be concluded from Table 3 that due to the difference in thecomposition itself, the best performances were slightly different. Theperformance value of the Comparative Example 9 was relatively large, andother performance values were basically at the same level. The heattreatment temperature ranged from 345 to 385° C. due to the differencein composition. In the stress experiment, the samples with differentcompositions having best performance after annealing were selected forstress sensibility experiments.

TABLE 3 Performance data of samples with different compositions afteroptimum heat treatment 1.35 T/50 Hz Best Thermal Composition Treatment PPe Group Fe Si B Temperature (W/kg) (VA/kg) Comparative 79 9 12 3850.121 0.145 Example 3 Example 4 80.5 8 11.5 355 0.106 0.131 Example 580.5 7.5 12 365 0.085 0.125 Example 6 80.5 7 12.5 365 0.09 0.12 Example12 79.5 8.5 12 385 0.103 0.137 Example 13 82.5 6.5 11 345 0.110 0.145Comparative 80.5 6 13.5 355 0.093 0.13 Example 7 Comparative 83 6.5 10.5345 0.145 0.167 Example 9

TABLE 4 Loss values and deterioration coefficient under different gaugefactors P(W/kg) Gauge Factor Category 0% 2.0% 4.0% 6.0% 8.0% 10.0%Comparative 0.121 0.134 0.144 0.15 0.178 0.235 Example 3 Example 4 0.1060.109 0.114 0.118 0.125 0.156 Example 5 0.085 0.089 0.093 0.098 0.1030.121 Example 6 0.09 0.093 0.098 0.102 0.107 0.123 Example 12 0.1030.109 0.113 0.121 0.137 0.151 Example 13 0.110 0.116 0.125 0.138 0.1480.16 Comparative 0.093 0.105 0.109 0.115 0.128 0.165 Example 7Comparative 0.145 0.165 0.173 0.186 0.198 0.258 Example 9

TABLE 4 Loss values and deterioration coefficient under different gaugefactors (Continued Table) Deterioration Coefficient of P Maximum GaugeFactor Gauge Category 2.0% 4.0% 6.0% 8.0% 10.0% Factor Comparative 10.7%19.0% 24.0% 47.1% 94.2% 8.0% Example 3 Example 4 2.8% 7.5% 11.3% 17.9%47.2% 10.0% Example 5 4.7% 9.4% 15.3% 21.2% 42.4% 10.0% Example 6 3.3%8.9% 13.3% 18.9% 36.7% 10.0% Example 12 5.8% 9.7% 17.5% 33.0% 46.6%10.0% Example 13 5.5% 13.6% 25.5% 34.5% 45.5% 10.0% Comparative 12.9%17.2% 23.7% 37.6% 77.4% 8.0% Example 7 Comparative 13.8% 19.3% 28.3%36.6% 77.9% 8.0% Example 9

TABLE 5 Excitation power and deterioration coefficient under differentgauge factors Pe(VA/kg) Gauge Factor Category 0% 2.0% 4.0% 6.0% 8.0%10.0% Comparative 0.145 0.18 0.351 0.507 1.022 1.441 Example 3 Example 40.131 0.144 0.165 0.176 0.24 0.302 Example 5 0.125 0.138 0.16 0.1850.205 0.401 Example 6 0.12 0.132 0.154 0.176 0.207 0.354 Example 120.137 0.148 0.164 0.185 0.215 0.367 Example 13 0.145 0.158 0.179 0.1920.208 0.42 Comparative 0.13 0.178 0.33 0.428 0.854 1.025 Example 7Comparative 0.167 0.195 0.225 0.403 0.784 0.998 Example 9

TABLE 5 Excitation power and deterioration coefficient under differentgauge factors (Continued table) Deterioration Coefficient of Pe MaximumGauge Factor Gauge Category 2.0% 4.0% 6.0% 8.0% 10.0% Factor Comparative24.1% 142.1% 249.7% 604.8% 893.8% 2.0% Example 3 Example 4 9.9% 26.0%34.4% 83.2% 130.5% 6.0% Example 5 10.4% 28.0% 48.0% 64.0% 220.8% 6.0%Example 6 10.0% 28.3% 46.7% 72.5% 195.0% 6.0% Example 12 8.0% 19.7%35.0% 56.9% 167.9% 6.0% Example 13 9.0% 23.4% 32.4% 43.4% 189.7% 8.0%Comparative 36.9% 153.8% 229.2% 556.9% 688.5% 2.0% Example 7 Comparative16.8% 34.7% 141.3% 369.5% 497.6% 4.0% Example 9

Tables 4 and 5 clearly showed that iron-based amorphous alloys undergonea certain degree of performance deterioration due to the influence ofstress, and the performance deterioration coefficient increased as thedeformation coefficient increased. Comparing the loss and the excitationpower of each component, it could be found that the deterioration of theexcitation power significantly exceeded its loss. The allowabledeterioration coefficient of excitation power was 6%, while theallowable deterioration coefficient of loss was 10%. That is, theapplication of external stress to the amorphous strip has a greatereffect on the excitation power.

Comparing the examples with comparative examples, it could be found thatthere was a big difference in the performance deterioration coefficientof strips with different compositions when subjected to stress. The lossof the amorphous alloy strips in examples 4 to 6 and 12 to 13 allowed agauge factor of 10%, and excitation power of examples 4 to 6 and 12 to13 allowed a deterioration coefficient of 6%. Considering the bucketeffect of the performance comprehensively, the allowable deteriorationcoefficient of the embodiments was 6%. The allowable gauge factors forthe losses and excitation power of the comparative example were 8% and2%, respectively, and the allowable deterioration factor for thecomparative example was 2%. In view of above, the annealedpost-amorphous tape embodiment had significant advantages in theresistance to stress sensibility, allowing greater deformation andensuring that the material properties were within an acceptable range.

The above description of the embodiments is merely for helping tounderstand the method of the present disclosure and its core idea. Itshould be pointed out that one of ordinary skill in the art can alsomake several improvements and modifications to the present disclosurewithout departing from the principles of the present invention, andthese improvements and modifications also fall into the protection scopeof the claims of the present invention.

The above description of the disclosed embodiments enables one ofordinary skill in the art to implement or use the present invention.Various modifications to these embodiments will be readily apparent toone of ordinary skill in the art, and the general principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present disclosure will notbe limited to the embodiments shown herein but will be consistent withthe widest scope consistent with the principles and novel featuresdisclosed herein.

1. An iron-based amorphous alloy represented by formula (I):Fe_(a)B_(b)Si_(c)   (I); wherein a, b and c are each independentlyatomic percentages of corresponding components, 79.5≤a≤82.5,11.0≤b≤13.5, 6.5≤c≤8.5, and a+b+c=100.
 2. The iron-base amorphous alloyaccording to claim 1, wherein the saturation magnetic induction of theiron-based amorphous alloy is ≥1.60 T.
 3. The iron-base amorphous alloyaccording to claim 1, wherein the atomic percentage of Fe is80.0≤a≤81.5.
 4. The iron-base amorphous alloy according to claim 1,wherein the atomic percentage of B is 11.0≤b≤12.5.
 5. The iron-baseamorphous alloy according to claim 1, wherein the atomic percentage ofSi is 7.0≤c≤8.0.
 6. The iron-base amorphous alloy according to claim 1,wherein in the iron-based amorphous alloy a=80.0, 12.0≤b≤13.0, and7.0≤c≤8.0.
 7. The iron-base amorphous alloy according to claim 1,wherein in the iron-based amorphous alloy a=80.5, 11.5≤b≤12.5, and7.0≤c≤8.0.
 8. The iron-base amorphous alloy according to claim 1,wherein in the iron-based amorphous alloy 81.0≤a≤81.5, 11.0≤b≤13.0, and7.0≤c≤8.0.
 9. A method for preparing an iron-based amorphous alloy striprepresented by formula (I), comprising: preparing raw materialsaccording to the atomic percentages indicated in formula (I); smeltingthe raw materials; heating and insulating the molten liquid aftersmelting; performing single roller rapid quenching to obtain theiron-based amorphous alloy strip;Fe_(a)B_(b)Si_(c)   (I); wherein a, b and c are each independentlyatomic percentages of corresponding components; 79.5≤a≤82.5,11.0≤b≤13.5, 6.5≤c≤8.5, and a+b+c=100.
 10. The method according to claim9, further comprising subjecting the iron-based amorphous alloy to heattreatment after the single roller rapid quenching.
 11. The methodaccording to claim 10, wherein prior to the heat treatment, furthercomprising winding the iron-based amorphous alloy into a sample ringwith an inside diameter of 50.5 mm and an outside diameter from 53.5 to54 mm, wherein allowable gauge factor of the sample ring loss is 10.0%and allowable gauge factor of the excitation power is 6% after heattreatment.
 12. The method according to the claim 10, wherein thecoercive force of an iron-based amorphous alloy strip after heattreatment is ≤3.5 A/m; under a condition of 50 Hz and 1.35 T, excitationpower of the iron-based amorphous alloy strip after heat treatment is≤0.1450 VA/kg, and core loss is ≤0.1100 W/kg; and under a condition of50 Hz and 1.40 T, excitation power of the iron-based amorphous alloystrip after heat treatment is ≤0.1700 VA/kg, and core loss is ≤0.1500W/kg.
 13. The method according to claim 10, wherein the iron-basedamorphous alloy strip is in completely amorphous phase with a limitthickness of at least 75 μm and a shearable limit thickness of at least29 μm.